The invention relates to X-ray spot-film devices having diaphragms which are arranged close to the film. One diaphragm in each device has horizontal diaphragm edges extending symmetrically with respect to a horizontal center line. Another diaphragm has vertically extending diaphragm edges.
Such a spot-film device is described in German Offenlegungsschrift No. 2842659. The terms "horizontal" and "vertical" relate to the spot-film device in a standing position, with the two diaphragm assemblies extending in vertical planes. The term "center line" designates a horizontal or vertical straight line passing through the center of the exposure or radiographic field struck by radiation.
In FIG. 4 of the known device, one diaphragm comprises a U-shaped diaphragm plate, and the other diaphragm comprises a rectangular diaphragm plate. In order to limit the width of the exposure field, the two diaphragm plates are moved toward each other so that the exposure field remains between the vertical edges facing each other. In order to limit the height and width of the exposure field, the two diaphragm plates are displaced along each other so that the exposure field is limited by the horizontally arranged U of the first diaphragm plate and by one vertical diaphragm edge of the second diaphragm plate.
A disadvantage of the known X-ray spot-film device is that when limiting the width of the exposure field, the exposure field has a predetermined height. Moreover, the control of each of the two diaphragm plates depends both upon the height and width of the exposure field. and the
Furthermore, spot-film devices are known, in which the width of the exposure field is determined by two diaphragm plates which are coupled to each other so that their vertical edges facing each other invariably extend symmetrically about the vertical center line. For exposures, in which the height of the exposure should be limited, exchangeable plates or compression chambers can be arranged in the radiation path. However, exchanging plates has a disturbing effect during the examination and is not practicable in various kinds of examination.